Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-NetBSD identifier is obsolete, drop -NetBSD

The SPDX folks have obsoleted the BSD-2-Clause-NetBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

makefs: correct iso9660 Rock Ridge NM values

These are not actually used by makefs (yet), but ought to match the
spec.

See RRIP 4.1.4 Description of the "NM" System Use Entry for details.

PR: 203531
Sponsored by: The FreeBSD Foundation

makefs: correct iso9660 Rock Ridge TF timestamps

The bit definitions for the TF_* timestamp bits (TF_MODIFY, etc.) were
incorrect, and timestamps were written in the wrong order.

See RRIP 4.1.6 Description of the "TF" System Use Entry for details.

PR: 203531
Reported by: Thomas Schmitt <scdbackup@gmx.net>
Reviewed by: jrtc27, kevans
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39221

makefs: whitespace cleanup (remove space before tab)

MFC after: 1 week

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.

makefs: eliminate global cd9660 structure

For diff reduction with NetBSD

NetBSD file versions:
cd9660.c 1.39
cd9660.h 1.19
cd9660/cd9660_debug.c 1.12
cd9660/cd9660_eltorito.c 1.20
cd9660/cd9660_write.c 1.16
cd9660/iso9660_rrip.c 1.12
cd9660/iso9660_rrip.h 1.6

Reviewed by: ngie
Obtained from: NetBSD
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D9627

Record the IEEE P1282 Rock Ridge version 1.12 POSIX File Serial Number,
i. e. the POSIX:5.6.1 st_ino field, which can be used to detect hard links
in the file system. This is also the default in mkisofs(8) and according to
its man page, no system only being able to cope with Rock Ridge version 1.10
is known to exist.

PR: 185138
Submitted by: Kurt Lidl
MFC after: 1 week

Sync with the latest version from NetBSD. It notably addds ISO9660 support.

Submitted by: bapt